Objective To detect the changes on the expression of putative drug effiux genes caused by isoniazid-inducement in single resistance to the isoniazid Mycobacterium tuberculosis (M.tuberculosis) clinical isolates,for exploring the putative effiux genes which causing M.tuberculosis isoniazid resistance as well as the mechanism related to high expression of the putative effiux genes.Methods We selected 35 M.tuberculosis clinical isolates which were only resistant to isoniazid as well as 10 sensitive M.tuberculosis clinical isolates and using H37Rv as control.Each strain was cultured in 7H9 liquid medium without isoniazid and with subinhibitory isoniazid concentration (1/4 MIC) induction.After RNA extraction and reverse transcription,real-time PCR was conducted to assess the expression changes of 27 putative drug effiux pump genes with formula 2-△△CT to calculate the expression of each putative drug efflux pump genes.Results Of the 27 putative genes,13 of them were expressed at high level.High expression of Rv1258c gene had the maximum number of 6strains,followed by high expression of Rv0849 and Rv2265 which both had 5 strains.Fourteen strains (40.00％) out of the 35 strains had high expression pump genes.Six strains (17.14％) had only one highly expressed putative efflux pump gene.Eight strains (22.86％) had two or more highly expressed putative effiux pump genes,including two,four,five,seven genes that highly expressed in 4,2,1,1strains respectively.For the 27 putative genes,ten sensitive strains and H37Rv did not show highly expressed genes.Conclusion Rv1258c,Rv2265,Rv0849,etc.genes might be the putative effiux pumps genes of M.tuberculosis resistant to isoniazid.Isoniazid might serve as the inducer of M.tuberculosis part putative effiux pump genes,inducing activation and causing high expression of these putative effiux pump genes.